The present invention relates to the technical field of optically inspecting translucent or transparent hollow containers or objects that are at high temperature.
The invention relates more particularly to optically inspecting objects such as glass bottles or flasks leaving a manufacturing or forming machine at a high rate.
In conventional manner, a forming machine includes a plurality of cavities, each having a mold in which the container takes on its final shape at high temperature. At the outlet from the forming machine, the containers are moved so as to constitute a row on a transport conveyor causing the containers to pass in succession through various stations for treatments such as spraying and annealing.
It would be advantageous to identify a forming defect at the outlet from the forming machine as soon as possible and before the various treatment stations in order to be able to correct the defect as soon as possible on the forming machine. It is thus advantageous in particular to detect dimensional deviations or deformations of the containers that are associated directly with settings of the forming process, so as to enable the process to be corrected as quickly as possible in the event of any drift.
In the state of the art, it is known to install a contactless optical inspection system at the outlet from the forming machine enabling containers to be inspected while they are still hot, i.e. at a temperature lying in the range 300° C. to 600° C.
For example, patent EP 0 177 004 proposes a system for contactless inspection of still-hot glass containers immediately after they have been formed. That system has a lighting source arranged on one side of the conveyor and a linear camera mounted on the side of the conveyor opposite from its side fitted with the lighting source. The containers move in line between the lighting source and the camera so that they are back-lighted, insofar as the light used for this observation travels from the source to the containers and from the containers to the site of observation.
Independently of that automated inspection system, the operators controlling the forming machine frequently have available a lighting source referred to as a “bottle scanner” that makes it possible to obtain a visual estimate of the quality of the containers leaving the forming machine. The bottle scanner is installed along the conveyor located at the outlet from the forming machine, being situated on the side of the conveyor that is remote from its side where the operators are to be found so that the operators observe the containers while they are back-lit.
Unfortunately, it should be observed that in numerous applications, the space available at the outlet from the forming machine does not leave room for a bottle scanner and an automatic inspection system to be installed.